In the packaging of integrated circuits, package components, such as device dies and package substrates, are typically stacked through flip chip bonding. To protect the solder regions between the stacked package components, an underfill is disposed between the stacked package components. A molding compound may then be molded on the stacked package components through over-molding.
The conventional molding methods include compression molding and transfer molding. Compression molding may be used for the over-molding. Since the compression molding cannot be used to fill the underfill into the gaps between the stacked dies, the underfill needs to be dispensed in separate steps other than the compression molding. On the other hand, transfer molding may be used to fill a molding underfill into the gap between, and over, the stacked package components. Accordingly, transfer molding may be used to dispense the underfill and the molding compound in the same process step. Transfer molding, however, cannot be used on the packages including round wafers due to non-uniform dispensing of the molding compound.